linux.git/drivers/dma/idxd/submit.c, branch v6.0 Linux kernel source tree dmaengine: idxd: fix retry value to be constant for duration of function call 2022-04-20T11:54:42+00:00 Dave Jiang dave.jiang@intel.com 2022-04-18T21:33:21+00:00 bc3452cdfc468a65965d0ac397c940acb787ea4d When retries is compared to wq->enqcmds_retries each loop of idxd_enqcmds(), wq->enqcmds_retries can potentially changed by user. Assign the value of retries to wq->enqcmds_retries during initialization so it is the original value set when entering the function. Fixes: 7930d8553575 ("dmaengine: idxd: add knob for enqcmds retries") Suggested-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/165031760154.3658664.1983547716619266558.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
When retries is compared to wq->enqcmds_retries each loop of idxd_enqcmds(),
wq->enqcmds_retries can potentially changed by user. Assign the value
of retries to wq->enqcmds_retries during initialization so it is the
original value set when entering the function.

Fixes: 7930d8553575 ("dmaengine: idxd: add knob for enqcmds retries")
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/165031760154.3658664.1983547716619266558.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: match type for retries var in idxd_enqcmds() 2022-04-20T11:54:42+00:00 Dave Jiang dave.jiang@intel.com 2022-04-18T21:31:10+00:00 5d9d16e5aa0cf023e600bf716239fd9caa2d4148 wq->enqcmds_retries is defined as unsigned int. However, retries on the stack is defined as int. Change retries to unsigned int to compare the same type. Fixes: 7930d8553575 ("dmaengine: idxd: add knob for enqcmds retries") Suggested-by: Thiago Macieira <thiago.macieira@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/165031747059.3658198.6035308204505664375.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
wq->enqcmds_retries is defined as unsigned int. However, retries on the
stack is defined as int. Change retries to unsigned int to compare the same
type.

Fixes: 7930d8553575 ("dmaengine: idxd: add knob for enqcmds retries")
Suggested-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/165031747059.3658198.6035308204505664375.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: embed irq_entry in idxd_wq struct 2022-01-05T07:41:21+00:00 Dave Jiang dave.jiang@intel.com 2021-12-13T18:51:23+00:00 ec0d64231615e50539d83516b974e7947d45fbce With irq_entry already being associated with the wq in a 1:1 relationship, embed the irq_entry in the idxd_wq struct and remove back pointers for idxe_wq and idxd_device. In the process of this work, clean up the interrupt handle assignment so that there's no decision to be made during submit call on where interrupt handle value comes from. Set the interrupt handle during irq request initialization time. irq_entry 0 is designated as special and is tied to the device itself. Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163942148362.2412839.12055447853311267866.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
With irq_entry already being associated with the wq in a 1:1 relationship,
embed the irq_entry in the idxd_wq struct and remove back pointers for
idxe_wq and idxd_device. In the process of this work, clean up the interrupt
handle assignment so that there's no decision to be made during submit
call on where interrupt handle value comes from. Set the interrupt handle
during irq request initialization time.

irq_entry 0 is designated as special and is tied to the device itself.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163942148362.2412839.12055447853311267866.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Merge branch 'fixes' into next 2022-01-05T07:18:05+00:00 Vinod Koul vkoul@kernel.org 2022-01-05T07:18:05+00:00 5cb664fbeba0a11592c1d2774833a4cc49d1ca19 We have a conflict in idxd driver between 'fixes' and 'next' and there are patches dependent on this so, merge the 'fixes' branch into next 
We have a conflict in idxd driver between 'fixes' and 'next' and there
are patches dependent on this so, merge the 'fixes' branch into next
dmaengine: idxd: add knob for enqcmds retries 2021-12-17T16:09:28+00:00 Dave Jiang dave.jiang@intel.com 2021-11-29T17:19:38+00:00 7930d85535751bc8b05c6731c6b79d874671f13c Add a sysfs knob to allow tuning of retries for the kernel ENQCMDS descriptor submission. While on host, it is not as likely that ENQCMDS return busy during normal operations due to the driver controlling the number of descriptors allocated for submission. However, when the driver is operating as a guest driver, the chance of retry goes up significantly due to sharing a wq with multiple VMs. A default value is provided with the system admin being able to tune the value on a per WQ basis. Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163820629464.2702134.7577370098568297574.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
Add a sysfs knob to allow tuning of retries for the kernel ENQCMDS
descriptor submission. While on host, it is not as likely that ENQCMDS
return busy during normal operations due to the driver controlling the
number of descriptors allocated for submission. However, when the driver is
operating as a guest driver, the chance of retry goes up significantly due
to sharing a wq with multiple VMs. A default value is provided with the
system admin being able to tune the value on a per WQ basis.

Suggested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163820629464.2702134.7577370098568297574.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: fix missed completion on abort path 2021-12-13T05:40:41+00:00 Dave Jiang dave.jiang@intel.com 2021-12-08T17:01:27+00:00 8affd8a4b5ce356c8900cfb037674f3a4a11fbdb Ming reported that with the abort path of the descriptor submission, there can be a window where a completed descriptor can be missed to be completed by the irq completion thread: CPU A CPU B Submit (successful) Submit (fail) irq_process_work_list() // empty llist_abort_desc() // remove all descs from pending list irq_process_pending_llist() // empty exit idxd_wq_thread() with no processing Add opportunistic descriptor completion in the abort path in order to remove the missed completion. Fixes: 6b4b87f2c31a ("dmaengine: idxd: fix submission race window") Reported-by: Ming Li <ming4.li@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163898288714.443911.16084982766671976640.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
Ming reported that with the abort path of the descriptor submission, there
can be a window where a completed descriptor can be missed to be completed
by the irq completion thread:

CPU A				CPU B
Submit (successful)

Submit (fail)
				irq_process_work_list() // empty

llist_abort_desc()
// remove all descs from pending list

				irq_process_pending_llist() // empty
				exit idxd_wq_thread() with no processing

Add opportunistic descriptor completion in the abort path in order to
remove the missed completion.

Fixes: 6b4b87f2c31a ("dmaengine: idxd: fix submission race window")
Reported-by: Ming Li <ming4.li@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163898288714.443911.16084982766671976640.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: handle interrupt handle revoked event 2021-11-22T05:51:26+00:00 Dave Jiang dave.jiang@intel.com 2021-10-26T21:36:41+00:00 56fc39f5a36794c4f27f5fee047b641eac3f5b89 "Interrupt handle revoked" is an event that happens when the driver is running on a guest kernel and the VM is migrated to a new machine. The device will trigger an interrupt that signals to the guest driver that the interrupt handles need to be replaced. The misc irq thread function calls a helper function to handle the event. The function uses the WQ percpu_ref to quiesce the kernel submissions. It then replaces the interrupt handles by requesting interrupt handle command for each I/O MSIX vector. Once the handle is updated, the driver will unblock the submission path to allow new submissions. The submitter will attempt to acquire a percpu_ref before submission. When the request fails, it will wait on the wq_resurrect 'completion'. The driver does anticipate the possibility of descriptors being submitted before the WQ percpu_ref is killed. If a descriptor has already been submitted, it will return with incorrect interrupt handle status. The descriptor will be re-submitted with the new interrupt handle on the completion path. For descriptors with incorrect interrupt handles, completion interrupt won't be triggered. At the completion of the interrupt handle refresh, the handling function will call idxd_int_handle_refresh_drain() to issue drain descriptors to each of the wq with associated interrupt handle. The drain descriptor will have interrupt request set but without completion record. This will ensure all descriptors with incorrect interrupt completion handle get drained and a completion interrupt is triggered for the guest driver to process them. Reviewed-by: Kevin Tian <kevin.tian@intel.com> Co-Developed-by: Sanjay Kumar <sanjay.k.kumar@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163528420189.3925689.18212568593220415551.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
"Interrupt handle revoked" is an event that happens when the driver is
running on a guest kernel and the VM is migrated to a new machine.
The device will trigger an interrupt that signals to the guest driver
that the interrupt handles need to be replaced.

The misc irq thread function calls a helper function to handle the
event. The function uses the WQ percpu_ref to quiesce the kernel
submissions. It then replaces the interrupt handles by requesting
interrupt handle command for each I/O MSIX vector. Once the handle is
updated, the driver will unblock the submission path to allow new
submissions.

The submitter will attempt to acquire a percpu_ref before submission. When
the request fails, it will wait on the wq_resurrect 'completion'.

The driver does anticipate the possibility of descriptors being submitted
before the WQ percpu_ref is killed. If a descriptor has already been
submitted, it will return with incorrect interrupt handle status. The
descriptor will be re-submitted with the new interrupt handle on the
completion path. For descriptors with incorrect interrupt handles,
completion interrupt won't be triggered.

At the completion of the interrupt handle refresh, the handling function
will call idxd_int_handle_refresh_drain() to issue drain descriptors to
each of the wq with associated interrupt handle. The drain descriptor will have
interrupt request set but without completion record. This will ensure all
descriptors with incorrect interrupt completion handle get drained and
a completion interrupt is triggered for the guest driver to process them.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Co-Developed-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163528420189.3925689.18212568593220415551.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: move interrupt handle assignment 2021-11-22T05:51:26+00:00 Dave Jiang dave.jiang@intel.com 2021-10-26T21:36:17+00:00 eb0cf33a91b46cd50b590d032471f7f977d5a92a In preparation of supporting interrupt handle revoke event, move the interrupt handle assignment to right before the descriptor to be submitted. This allows the interrupt handle revoke logic to assign the latest interrupt handle on submission. Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163528417767.3925689.7730411152122952808.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
In preparation of supporting interrupt handle revoke event, move the
interrupt handle assignment to right before the descriptor to be submitted.
This allows the interrupt handle revoke logic to assign the latest
interrupt handle on submission.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163528417767.3925689.7730411152122952808.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: int handle management refactoring 2021-11-22T05:51:26+00:00 Dave Jiang dave.jiang@intel.com 2021-10-26T21:36:10+00:00 8b67426e05584e956775f4b134596b56bc0d35e0 Attach int_handle to irq_entry. This removes the separate management of int handles and reduces the confusion of interating through int handles that is off by 1 count. Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163528417065.3925689.11505755433684476288.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
Attach int_handle to irq_entry. This removes the separate management of int
handles and reduces the confusion of interating through int handles that is
off by 1 count.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163528417065.3925689.11505755433684476288.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
dmaengine: idxd: rework descriptor free path on failure 2021-11-22T05:51:26+00:00 Dave Jiang dave.jiang@intel.com 2021-10-26T21:36:02+00:00 5d78abb6fbc974d601dd365b9ce39f320fb5ba79 Refactor the completion function to allow skipping of descriptor freeing on the submission failure path. This completely removes descriptor freeing from the submit failure path and leave the responsibility to the caller. Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Link: https://lore.kernel.org/r/163528416222.3925689.12859769271667814762.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org> 
Refactor the completion function to allow skipping of descriptor freeing on
the submission failure path. This completely removes descriptor freeing
from the submit failure path and leave the responsibility to the caller.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163528416222.3925689.12859769271667814762.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>